1. Field of the Invention
The present invention relates to AB block co-polymers comprising, as the A component, a triphenyl phosphine oxide (TPPO) monomer and, as the B component, another monomer which may be the same or different, and to ultra-high density, low loss, thin film capacitors containing these AB block co-polymers.
2. Description of the Background
Metallized film capacitors are utilized in a broad range of electrical and electronic components. Various dielectrics and different structures make these products suitable for versatile applications in automotive and entertainment electronics, telecommunications, and industrial and medical electronics (see U.S. Pat. Nos. 5,691,442; 6,040,416; 5,387,629; and 5,134,207).
Metallized film capacitors are generally used to store energy. Some applications use capacitors to perform specific functions such as filtering, timing, and decoupling. The advantages of metallized film capacitors include high temperature operation, exceptional stability, low power loss, close tolerance, long life, high reliability, and lower volume, cost, and weight.
Many different kinds of polymer film capacitors exist which are identified by the dielectric material that is used in their construction. Common dielectric materials used to make polymer film capacitors include polycarbonate, polyester, polypropylene, polystyrene and polysulfone. The use of these polymers allows for advanced electronic packaging techniques, resulting in improved system performance and reliability.
These conventional polymeric materials, however, have several disadvantages as a dielectric film material, including a great decrease in dielectric properties in a humid atmosphere, film forming difficulties, small dielectric constants, small energy storage density, and instability at increasingly high temperatures.
In conventional capacitors, the dielectric material exists in the form of thick layers which must be self-supporting and thick enough to sustain the necessary operating voltage and physical handling. The large thickness of the polymer sheets in this case reduces the energy storage density of the capacitors. In conventional capacitors which employ a polymer sheet as the dielectric material, the layer of dielectric material typically has a thickness of at least 3-6 microns. Because the ability of a capacitor to store energy is inversely proportional to the thickness of a dielectric material, reduction of the thickness of the base film is required to improve capacitance of the capacitor. Conventional polymer films cannot satisfy the requirement for the reduction of film thickness sufficiently, because a very thin film has poor workability or processability in the production step of capacitors.
In addition to the current need for thin film capacitors, persons skilled in the art are faced with many manufacturing limitations. The polymeric materials must satisfy a number of critical thermal, environmental, and electrical requirements to meet the required performance criteria for microelectronics applications. These desired attributes include thermal stability, low moisture uptake, high breakdown voltage, low dielectric constant, low loss tangent, low leakage current, high glass transition temperature, and low surface roughness. When attempting to increase the energy density, the dielectric constant and breakdown voltages should remain fixed due to fixed polymer chemistries. If the voltage of the capacitor is raised above the corona inception voltage, rapid degradation of the dielectrics can occur. Dielectric degradation by thermal loads and electrostrictive forces can occur in high voltage rates, e.g., dV/dt, and high rep-rate pulse applications.
Thus, a need currently exists in the art for ultra-high density low loss thin film dielectric polymers. A material with a high dielectric constant that is stable at high voltages and temperatures is needed.
The present invention relates to capacitors comprising AB block co-polymers and other polymers. Particularly, the present invention relates to ultra-high density, low loss, thin film capacitors containing AB block co-polymers comprising, as the A component, a triphenyl phosphine oxide (TPPO) monomer and, as the B component, another monomer which may be the same or different. Such capacitors provide a novel film capacitor free from the disadvantages and problems in existing film capacitors.
According to an embodiment of the invention, a capacitor comprises a triphenyl phosphine oxide film as a base dielectric film, wherein the triphenyl phosphine oxide film is fabricated containing a conducting PolyANiline(PAN) polymer layer located between the electrode and core polymer. The said triphenyl phosphine oxide film is stretched either bi-axially or uni-axially.
In another embodiment of the invention, a capacitor comprises a base dielectric, wherein said base dielectric is an A-B block co-polymer comprising a triphenyl phosphine oxide (TPPO) or TPPO derivative A block and a monomer B block, wherein the monomer B block is selected from a group consisting of Bisphenol-A (Bis-A PEPO), 4,4xe2x80x2-biphenol (BP-PEPO), and Hydroquinone (HQ-PEPO). The TPPO derivative comprises a moiety attached to a phenyl ring opposite to a P=O bond in said TPPO. Alternatively, the moiety is either an electron withdrawing moiety or an electron donating moiety. The electron withdrawing moiety is selected from a group consisting of F, Cl, CN, and NO. The electron donating moiety is selected from a group consisting of OCH3, CH3, and NHR2.
Other embodiments and advantages of the invention are set forth, in part, in the description which follows, and, in part, will be obvious from this description and may be learned from the practice of the invention.